Refactor devicelab logic to use TaskResult instead of JSON (#67550)

dev/devicelab/bin/run.dart

@@ -11,6 +11,7 @@ import 'package:path/path.dart' as path;
 import 'package:flutter_devicelab/framework/ab.dart';
 import 'package:flutter_devicelab/framework/manifest.dart';
 import 'package:flutter_devicelab/framework/runner.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 
 ArgResults args;
@@ -89,7 +90,7 @@ Future<void> main(List<String> rawArgs) async {
 Future<void> _runTasks() async {
   for (final String taskName in _taskNames) {
     section('Running task "$taskName"');
-    final Map<String, dynamic> result = await runTask(
+    final TaskResult result = await runTask(
       taskName,
       silent: silent,
       localEngine: localEngine,
@@ -101,7 +102,7 @@ Future<void> _runTasks() async {
     print(const JsonEncoder.withIndent('  ').convert(result));
     section('Finished task "$taskName"');
 
-    if (!(result['success'] as bool)) {
+    if (!result.succeeded) {
       exitCode = 1;
       if (exitOnFirstTestFailure) {
         return;
@@ -134,7 +135,7 @@ Future<void> _runABTest() async {
     section('Run #$i');
 
     print('Running with the default engine (A)');
-    final Map<String, dynamic> defaultEngineResult = await runTask(
+    final TaskResult defaultEngineResult = await runTask(
       taskName,
       silent: silent,
       deviceId: deviceId,
@@ -143,7 +144,7 @@ Future<void> _runABTest() async {
     print('Default engine result:');
     print(const JsonEncoder.withIndent('  ').convert(defaultEngineResult));
 
-    if (!(defaultEngineResult['success'] as bool)) {
+    if (!defaultEngineResult.succeeded) {
       stderr.writeln('Task failed on the default engine.');
       exit(1);
     }
@@ -151,7 +152,7 @@ Future<void> _runABTest() async {
     abTest.addAResult(defaultEngineResult);
 
     print('Running with the local engine (B)');
-    final Map<String, dynamic> localEngineResult = await runTask(
+    final TaskResult localEngineResult = await runTask(
       taskName,
       silent: silent,
       localEngine: localEngine,
@@ -162,7 +163,7 @@ Future<void> _runABTest() async {
     print('Task localEngineResult:');
     print(const JsonEncoder.withIndent('  ').convert(localEngineResult));
 
-    if (!(localEngineResult['success'] as bool)) {
+    if (!localEngineResult.succeeded) {
       stderr.writeln('Task failed on the local engine.');
       exit(1);
     }

dev/devicelab/bin/tasks/android_engine_dependency_proxy_test.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:flutter_devicelab/framework/apk_utils.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/android_obfuscate_test.dart

@@ -4,6 +4,7 @@
 
 import 'package:flutter_devicelab/framework/apk_utils.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/build_aar_module_test.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:flutter_devicelab/framework/apk_utils.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/build_aar_plugin_test.dart

@@ -5,6 +5,7 @@
 import 'dart:io';
 
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/build_ios_framework_module_test.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/framework/ios.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/build_mode_test.dart

@@ -10,6 +10,7 @@ import 'package:path/path.dart' as path;
 
 import 'package:flutter_devicelab/framework/adb.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 
 Future<String> runFlutterAndQuit(List<String> args, Device device) async {

dev/devicelab/bin/tasks/commands_test.dart

@@ -11,6 +11,7 @@ import 'package:vm_service_client/vm_service_client.dart';
 
 import 'package:flutter_devicelab/framework/adb.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 
 void main() {

dev/devicelab/bin/tasks/complex_layout_semantics_perf.dart

@@ -4,6 +4,7 @@
 
 import 'package:flutter_devicelab/framework/adb.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as p;
 

dev/devicelab/bin/tasks/dartdocs.dart

@@ -6,6 +6,7 @@ import 'dart:convert';
 import 'dart:io';
 
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/drive_perf_debug_warning.dart

@@ -4,6 +4,7 @@
 
 import 'package:flutter_devicelab/framework/adb.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 
 Future<String> _runWithMode(String mode, String deviceId) async {

dev/devicelab/bin/tasks/flutter_attach_test_fuchsia.dart

@@ -10,6 +10,7 @@ import 'dart:math';
 import 'package:path/path.dart' as path;
 import 'package:flutter_devicelab/framework/adb.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 
 void generateMain(Directory appDir, String sentinel) {

dev/devicelab/bin/tasks/flutter_gallery__transition_perf_with_semantics.dart

@@ -5,6 +5,7 @@
 import 'package:flutter_devicelab/tasks/gallery.dart';
 import 'package:flutter_devicelab/framework/adb.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 
 Future<void> main() async {
   deviceOperatingSystem = DeviceOperatingSystem.android;

dev/devicelab/bin/tasks/flutter_gallery_instrumentation_test.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:flutter_devicelab/framework/adb.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 
 // This test runs "//dev/integration_tests/flutter_gallery/test/live_smoketest.dart", which communicates

dev/devicelab/bin/tasks/flutter_gallery_v2_chrome_run_test.dart

@@ -9,6 +9,7 @@ import 'dart:io';
 import 'package:path/path.dart' as path;
 
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:flutter_devicelab/versions/gallery.dart' show galleryVersion;
 

dev/devicelab/bin/tasks/flutter_gallery_v2_web_compile_test.dart

@@ -7,6 +7,7 @@ import 'dart:io';
 import 'package:path/path.dart' as path;
 
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:flutter_devicelab/versions/gallery.dart' show galleryVersion;
 

dev/devicelab/bin/tasks/flutter_run_test.dart

@@ -10,6 +10,7 @@ import 'package:path/path.dart' as path;
 
 import 'package:flutter_devicelab/framework/adb.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 
 final Directory flutterGalleryDir = dir(path.join(flutterDirectory.path, 'examples/hello_world'));

dev/devicelab/bin/tasks/flutter_test_performance.dart

@@ -21,6 +21,7 @@ import 'dart:io';
 import 'package:path/path.dart' as path;
 
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 
 // Matches the output of the "test" package, e.g.: "00:01 +1 loading foo"

dev/devicelab/bin/tasks/gradle_fast_start_test.dart

@@ -4,6 +4,7 @@
 
 import 'package:flutter_devicelab/framework/apk_utils.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 
 Future<void> main() async {

dev/devicelab/bin/tasks/gradle_jetifier_test.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:flutter_devicelab/framework/apk_utils.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/gradle_migrate_settings_test.dart

@@ -5,6 +5,7 @@
 import 'dart:io';
 
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/gradle_non_android_plugin_test.dart

@@ -5,6 +5,7 @@
 import 'dart:io';
 
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/gradle_plugin_bundle_test.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:flutter_devicelab/framework/apk_utils.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/gradle_plugin_dependencies_test.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:flutter_devicelab/framework/apk_utils.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/gradle_plugin_fat_apk_test.dart

@@ -7,6 +7,7 @@ import 'dart:io';
 import 'package:path/path.dart' as path;
 import 'package:flutter_devicelab/framework/apk_utils.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 
 Future<void> main() async {

dev/devicelab/bin/tasks/gradle_plugin_light_apk_test.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:flutter_devicelab/framework/apk_utils.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 
 Future<void> main() async {

dev/devicelab/bin/tasks/gradle_plugins_without_annotations_test.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:flutter_devicelab/framework/apk_utils.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/gradle_r8_test.dart

@@ -5,6 +5,7 @@
 import 'dart:io';
 
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/ios_app_with_extensions_test.dart

@@ -7,6 +7,7 @@ import 'dart:io';
 
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/framework/ios.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 import 'package:meta/meta.dart';

dev/devicelab/bin/tasks/ios_content_validation_test.dart

@@ -7,6 +7,7 @@ import 'dart:io';
 import 'package:flutter_devicelab/framework/apk_utils.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/framework/ios.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/module_custom_host_app_name_test.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:flutter_devicelab/framework/apk_utils.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/module_host_with_custom_build_test.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:flutter_devicelab/framework/apk_utils.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/module_test.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:flutter_devicelab/framework/apk_utils.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/module_test_ios.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/framework/ios.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/plugin_dependencies_test.dart

@@ -6,6 +6,7 @@ import 'dart:convert';
 import 'dart:io';
 
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/plugin_lint_mac.dart

@@ -5,6 +5,7 @@
 import 'dart:io';
 
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/routing_test.dart

@@ -10,6 +10,7 @@ import 'package:path/path.dart' as path;
 
 import 'package:flutter_devicelab/framework/adb.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 
 void main() {

dev/devicelab/bin/tasks/run_release_test.dart

@@ -10,6 +10,7 @@ import 'package:path/path.dart' as path;
 
 import 'package:flutter_devicelab/framework/adb.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 
 void main() {

dev/devicelab/bin/tasks/service_extensions_test.dart

@@ -8,6 +8,7 @@ import 'dart:io';
 
 import 'package:flutter_devicelab/framework/adb.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 import 'package:vm_service_client/vm_service_client.dart';

dev/devicelab/bin/tasks/smoke_test_device.dart

@@ -2,8 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:flutter_devicelab/framework/framework.dart';
 import 'package:flutter_devicelab/framework/adb.dart';
+import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 
 /// Smoke test of a successful task.
 Future<void> main() async {

dev/devicelab/bin/tasks/smoke_test_failure.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 
 /// Smoke test of a task that fails by returning an unsuccessful response.
 Future<void> main() async {

dev/devicelab/bin/tasks/smoke_test_success.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 
 /// Smoke test of a successful task.
 Future<void> main() async {

dev/devicelab/bin/tasks/system_debug_ios.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:flutter_devicelab/framework/adb.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 
 import 'service_extensions_test.dart';

dev/devicelab/bin/tasks/technical_debt__cost.dart

@@ -6,6 +6,7 @@ import 'dart:convert';
 import 'dart:io';
 
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/time_to_development_benchmark__android.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:flutter_devicelab/framework/adb.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/bin/tasks/uncaught_image_error_linux.dart

@@ -7,6 +7,7 @@ import 'dart:io';
 
 import 'package:flutter_devicelab/framework/adb.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/lib/framework/ab.dart

@@ -5,6 +5,8 @@
 import 'dart:math' as math;
 import 'package:meta/meta.dart';
 
+import 'task_result.dart';
+
 const String kBenchmarkTypeKeyName = 'benchmark_type';
 const String kBenchmarkVersionKeyName = 'version';
 const String kLocalEngineKeyName = 'local_engine';
@@ -58,7 +60,7 @@ class ABTest {
   /// The result may contain multiple score keys.
   ///
   /// [result] is expected to be a serialization of [TaskResult].
-  void addAResult(Map<String, dynamic> result) {
+  void addAResult(TaskResult result) {
     if (_runEnd != null) {
       throw StateError('Cannot add results to ABTest after it is finalized');
     }
@@ -70,7 +72,7 @@ class ABTest {
   /// The result may contain multiple score keys.
   ///
   /// [result] is expected to be a serialization of [TaskResult].
-  void addBResult(Map<String, dynamic> result) {
+  void addBResult(TaskResult result) {
     if (_runEnd != null) {
       throw StateError('Cannot add results to ABTest after it is finalized');
     }
@@ -276,11 +278,9 @@ class _ScoreSummary {
   }
 }
 
-void _addResult(Map<String, dynamic> result, Map<String, List<double>> results) {
-  final List<String> scoreKeys = (result['benchmarkScoreKeys'] as List<dynamic>).cast<String>();
-  final Map<String, dynamic> data = result['data'] as Map<String, dynamic>;
-  for (final String scoreKey in scoreKeys) {
-    final double score = (data[scoreKey] as num).toDouble();
+void _addResult(TaskResult result, Map<String, List<double>> results) {
+  for (final String scoreKey in result.benchmarkScoreKeys) {
+    final double score = (result.data[scoreKey] as num).toDouble();
     results.putIfAbsent(scoreKey, () => <double>[]).add(score);
   }
 }

dev/devicelab/lib/framework/apk_utils.dart

@@ -5,9 +5,9 @@
 import 'dart:io';
 
 import 'package:path/path.dart' as path;
-import 'package:flutter_devicelab/framework/framework.dart';
-import 'package:flutter_devicelab/framework/utils.dart';
 
+import 'task_result.dart';
+import 'utils.dart';
 
 final String platformLineSep = Platform.isWindows ? '\r\n' : '\n';
 

dev/devicelab/lib/framework/framework.dart

@@ -13,6 +13,7 @@ import 'package:logging/logging.dart';
 import 'package:stack_trace/stack_trace.dart';
 
 import 'running_processes.dart';
+import 'task_result.dart';
 import 'utils.dart';
 
 /// Represents a unit of work performed in the CI environment that can
@@ -185,102 +186,3 @@ class _TaskRunner {
     return completer.future;
   }
 }
-
-/// A result of running a single task.
-class TaskResult {
-  /// Constructs a successful result.
-  TaskResult.success(this.data, {
-    this.benchmarkScoreKeys = const <String>[],
-    this.detailFiles,
-  })
-      : succeeded = true,
-        message = 'success' {
-    const JsonEncoder prettyJson = JsonEncoder.withIndent('  ');
-    if (benchmarkScoreKeys != null) {
-      for (final String key in benchmarkScoreKeys) {
-        if (!data.containsKey(key)) {
-          throw 'Invalid benchmark score key "$key". It does not exist in task '
-              'result data ${prettyJson.convert(data)}';
-        } else if (data[key] is! num) {
-          throw 'Invalid benchmark score for key "$key". It is expected to be a num '
-              'but was ${data[key].runtimeType}: ${prettyJson.convert(data[key])}';
-        }
-      }
-    }
-  }
-
-  /// Constructs a successful result using JSON data stored in a file.
-  factory TaskResult.successFromFile(File file,
-      {List<String> benchmarkScoreKeys}) {
-    return TaskResult.success(
-      json.decode(file.readAsStringSync()) as Map<String, dynamic>,
-      benchmarkScoreKeys: benchmarkScoreKeys,
-    );
-  }
-
-  /// Constructs an unsuccessful result.
-  TaskResult.failure(this.message)
-      : succeeded = false,
-        data = null,
-        detailFiles = null,
-        benchmarkScoreKeys = const <String>[];
-
-  /// Whether the task succeeded.
-  final bool succeeded;
-
-  /// Task-specific JSON data
-  final Map<String, dynamic> data;
-
-  /// Files containing detail on the run (e.g. timeline trace files)
-  final List<String> detailFiles;
-
-  /// Keys in [data] that store scores that will be submitted to Cocoon.
-  ///
-  /// Each key is also part of a benchmark's name tracked by Cocoon.
-  final List<String> benchmarkScoreKeys;
-
-  /// Whether the task failed.
-  bool get failed => !succeeded;
-
-  /// Explains the result in a human-readable format.
-  final String message;
-
-  /// Serializes this task result to JSON format.
-  ///
-  /// The JSON format is as follows:
-  ///
-  ///     {
-  ///       "success": true|false,
-  ///       "data": arbitrary JSON data valid only for successful results,
-  ///       "detailFiles": list of filenames containing detail on the run
-  ///       "benchmarkScoreKeys": [
-  ///         contains keys into "data" that represent benchmarks scores, which
-  ///         can be uploaded, for example. to golem, valid only for successful
-  ///         results
-  ///       ],
-  ///       "reason": failure reason string valid only for unsuccessful results
-  ///     }
-  Map<String, dynamic> toJson() {
-    final Map<String, dynamic> json = <String, dynamic>{
-      'success': succeeded,
-    };
-
-    if (succeeded) {
-      json['data'] = data;
-      if (detailFiles != null)
-        json['detailFiles'] = detailFiles;
-      json['benchmarkScoreKeys'] = benchmarkScoreKeys;
-    } else {
-      json['reason'] = message;
-    }
-
-    return json;
-  }
-
-  @override
-  String toString() => message;
-}
-
-class TaskResultCheckProcesses extends TaskResult {
-  TaskResultCheckProcesses() : super.success(null);
-}

dev/devicelab/lib/framework/runner.dart

@@ -12,6 +12,8 @@ import 'package:vm_service_client/vm_service_client.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:flutter_devicelab/framework/adb.dart';
 
+import 'task_result.dart';
+
 /// Runs a task in a separate Dart VM and collects the result using the VM
 /// service protocol.
 ///
@@ -20,7 +22,7 @@ import 'package:flutter_devicelab/framework/adb.dart';
 ///
 /// Running the task in [silent] mode will suppress standard output from task
 /// processes and only print standard errors.
-Future<Map<String, dynamic>> runTask(
+Future<TaskResult> runTask(
   String taskName, {
   bool silent = false,
   String localEngine,
@@ -79,7 +81,8 @@ Future<Map<String, dynamic>> runTask(
 
   try {
     final VMIsolateRef isolate = await _connectToRunnerIsolate(await uri.future);
-    final Map<String, dynamic> taskResult = await isolate.invokeExtension('ext.cocoonRunTask') as Map<String, dynamic>;
+    final Map<String, dynamic> taskResultJson = await isolate.invokeExtension('ext.cocoonRunTask') as Map<String, dynamic>;
+    final TaskResult taskResult = TaskResult.fromJson(taskResultJson);
     await runner.exitCode;
     return taskResult;
   } finally {

dev/devicelab/lib/framework/task_result.dart

@@ -0,0 +1,117 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:convert';
+import 'dart:io';
+
+/// A result of running a single task.
+class TaskResult {
+  /// Constructs a successful result.
+  TaskResult.success(this.data, {
+    this.benchmarkScoreKeys = const <String>[],
+    this.detailFiles,
+  })
+      : succeeded = true,
+        message = 'success' {
+    const JsonEncoder prettyJson = JsonEncoder.withIndent('  ');
+    if (benchmarkScoreKeys != null) {
+      for (final String key in benchmarkScoreKeys) {
+        if (!data.containsKey(key)) {
+          throw 'Invalid benchmark score key "$key". It does not exist in task '
+              'result data ${prettyJson.convert(data)}';
+        } else if (data[key] is! num) {
+          throw 'Invalid benchmark score for key "$key". It is expected to be a num '
+              'but was ${data[key].runtimeType}: ${prettyJson.convert(data[key])}';
+        }
+      }
+    }
+  }
+
+  /// Constructs a successful result using JSON data stored in a file.
+  factory TaskResult.successFromFile(File file,
+      {List<String> benchmarkScoreKeys}) {
+    return TaskResult.success(
+      json.decode(file.readAsStringSync()) as Map<String, dynamic>,
+      benchmarkScoreKeys: benchmarkScoreKeys,
+    );
+  }
+
+  /// Constructs a [TaskResult] from JSON.
+  factory TaskResult.fromJson(Map<String, dynamic> json) {
+    final bool success = json['success'] as bool;
+    if (success) {
+      final List<String> benchmarkScoreKeys = (json['benchmarkScoreKeys'] as List<dynamic> ?? <String>[]).cast<String>();
+      return TaskResult.success(json['data'] as Map<String, dynamic>,
+          benchmarkScoreKeys: benchmarkScoreKeys);
+    }
+
+    return TaskResult.failure(json['reason'] as String);
+  }
+
+  /// Constructs an unsuccessful result.
+  TaskResult.failure(this.message)
+      : succeeded = false,
+        data = null,
+        detailFiles = null,
+        benchmarkScoreKeys = const <String>[];
+
+  /// Whether the task succeeded.
+  final bool succeeded;
+
+  /// Task-specific JSON data
+  final Map<String, dynamic> data;
+
+  /// Files containing detail on the run (e.g. timeline trace files)
+  final List<String> detailFiles;
+
+  /// Keys in [data] that store scores that will be submitted to Cocoon.
+  ///
+  /// Each key is also part of a benchmark's name tracked by Cocoon.
+  final List<String> benchmarkScoreKeys;
+
+  /// Whether the task failed.
+  bool get failed => !succeeded;
+
+  /// Explains the result in a human-readable format.
+  final String message;
+
+  /// Serializes this task result to JSON format.
+  ///
+  /// The JSON format is as follows:
+  ///
+  ///     {
+  ///       "success": true|false,
+  ///       "data": arbitrary JSON data valid only for successful results,
+  ///       "detailFiles": list of filenames containing detail on the run
+  ///       "benchmarkScoreKeys": [
+  ///         contains keys into "data" that represent benchmarks scores, which
+  ///         can be uploaded, for example. to golem, valid only for successful
+  ///         results
+  ///       ],
+  ///       "reason": failure reason string valid only for unsuccessful results
+  ///     }
+  Map<String, dynamic> toJson() {
+    final Map<String, dynamic> json = <String, dynamic>{
+      'success': succeeded,
+    };
+
+    if (succeeded) {
+      json['data'] = data;
+      if (detailFiles != null)
+        json['detailFiles'] = detailFiles;
+      json['benchmarkScoreKeys'] = benchmarkScoreKeys;
+    } else {
+      json['reason'] = message;
+    }
+
+    return json;
+  }
+
+  @override
+  String toString() => message;
+}
+
+class TaskResultCheckProcesses extends TaskResult {
+  TaskResultCheckProcesses() : super.success(null);
+}

dev/devicelab/lib/framework/utils.dart

@@ -12,7 +12,7 @@ import 'package:path/path.dart' as path;
 import 'package:process/process.dart';
 import 'package:stack_trace/stack_trace.dart';
 
-import 'framework.dart';
+import 'task_result.dart';
 
 /// Virtual current working directory, which affect functions, such as [exec].
 String cwd = Directory.current.path;

dev/devicelab/lib/tasks/analysis.dart

@@ -6,7 +6,7 @@ import 'dart:io';
 
 import 'package:path/path.dart' as path;
 
-import '../framework/framework.dart';
+import '../framework/task_result.dart';
 import '../framework/utils.dart';
 
 /// Run each benchmark this many times and compute average, min, max.

dev/devicelab/lib/tasks/build_benchmarks.dart

@@ -5,6 +5,7 @@
 import 'dart:io';
 
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:path/path.dart' as path;
 

dev/devicelab/lib/tasks/defines_task.dart

@@ -5,7 +5,7 @@
 import 'dart:io';
 
 import '../framework/adb.dart';
-import '../framework/framework.dart';
+import '../framework/task_result.dart';
 import '../framework/utils.dart';
 
 Future<TaskResult> runDartDefinesTask() async {

dev/devicelab/lib/tasks/gallery.dart

@@ -6,8 +6,10 @@ import 'dart:convert';
 import 'dart:io';
 import 'dart:math' as math;
 
+
 import '../framework/adb.dart';
 import '../framework/framework.dart';
+import '../framework/task_result.dart';
 import '../framework/utils.dart';
 
 TaskFunction createGalleryTransitionTest({bool semanticsEnabled = false}) {

dev/devicelab/lib/tasks/hot_mode_tests.dart

@@ -10,6 +10,7 @@ import 'package:path/path.dart' as path;
 
 import '../framework/adb.dart';
 import '../framework/framework.dart';
+import '../framework/task_result.dart';
 import '../framework/utils.dart';
 
 final Directory _editedFlutterGalleryDir = dir(path.join(Directory.systemTemp.path, 'edited_flutter_gallery'));

dev/devicelab/lib/tasks/integration_tests.dart

@@ -4,6 +4,7 @@
 
 import '../framework/adb.dart';
 import '../framework/framework.dart';
+import '../framework/task_result.dart';
 import '../framework/utils.dart';
 
 TaskFunction createChannelsIntegrationTest() {

dev/devicelab/lib/tasks/integration_ui.dart

@@ -5,7 +5,7 @@
 import 'dart:io';
 
 import '../framework/adb.dart';
-import '../framework/framework.dart';
+import '../framework/task_result.dart';
 import '../framework/utils.dart';
 
 Future<TaskResult> runEndToEndTests() async {

dev/devicelab/lib/tasks/microbenchmarks.dart

@@ -10,6 +10,7 @@ import 'package:path/path.dart' as path;
 
 import 'package:flutter_devicelab/framework/adb.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 
 /// Creates a device lab task that runs benchmarks in

dev/devicelab/lib/tasks/new_gallery.dart

@@ -7,7 +7,7 @@ import 'dart:io';
 import 'package:flutter_devicelab/tasks/perf_tests.dart';
 
 
-import '../framework/framework.dart';
+import '../framework/task_result.dart';
 import '../framework/utils.dart';
 import '../versions/gallery.dart' show galleryVersion;
 

dev/devicelab/lib/tasks/perf_tests.dart

@@ -12,6 +12,7 @@ import 'package:path/path.dart' as path;
 
 import 'package:flutter_devicelab/framework/adb.dart';
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 import 'package:flutter_devicelab/tasks/track_widget_creation_enabled_task.dart';
 

dev/devicelab/lib/tasks/plugin_tests.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:path/path.dart' as path;
 import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 
 /// Combines several TaskFunctions with trivial success value into one.

dev/devicelab/lib/tasks/run_without_leak.dart

@@ -10,6 +10,7 @@ import 'package:path/path.dart' as path;
 
 import '../framework/adb.dart';
 import '../framework/framework.dart';
+import '../framework/task_result.dart';
 import '../framework/utils.dart';
 
 TaskFunction createRunWithoutLeakTest(dynamic dir) {

dev/devicelab/lib/tasks/track_widget_creation_enabled_task.dart

@@ -9,7 +9,7 @@ import 'package:vm_service/vm_service.dart';
 import 'package:vm_service/vm_service_io.dart';
 import 'package:flutter_devicelab/framework/adb.dart';
 import 'package:path/path.dart' as path;
-import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 
 final Directory integrationTestDir = Directory(

dev/devicelab/lib/tasks/web_benchmarks.dart

@@ -14,7 +14,7 @@ import 'package:shelf/shelf_io.dart' as shelf_io;
 import 'package:shelf_static/shelf_static.dart';
 
 import 'package:flutter_devicelab/framework/browser.dart';
-import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 import 'package:flutter_devicelab/framework/utils.dart';
 
 /// The port number used by the local benchmark server.

dev/devicelab/lib/tasks/web_dev_mode_tests.dart

@@ -9,6 +9,7 @@ import 'dart:io';
 import 'package:path/path.dart' as path;
 
 import '../framework/framework.dart';
+import '../framework/task_result.dart';
 import '../framework/utils.dart';
 
 final Directory _editedFlutterGalleryDir = dir(path.join(Directory.systemTemp.path, 'edited_flutter_gallery'));

dev/devicelab/test/ab_test.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'package:flutter_devicelab/framework/ab.dart';
+import 'package:flutter_devicelab/framework/task_result.dart';
 
 import 'common.dart';
 
@@ -11,7 +12,8 @@ void main() {
     final ABTest ab = ABTest('engine', 'test');
 
     for (int i = 0; i < 5; i++) {
-      ab.addAResult(<String, dynamic>{
+      final TaskResult aResult = TaskResult.fromJson(<String, dynamic>{
+        'success': true,
         'data': <String, dynamic>{
           'i': i,
           'j': 10 * i,
@@ -19,14 +21,16 @@ void main() {
         },
         'benchmarkScoreKeys': <String>['i', 'j'],
       });
-
-      ab.addBResult(<String, dynamic>{
+      ab.addAResult(aResult);
+      final TaskResult bResult = TaskResult.fromJson(<String, dynamic>{
+        'success': true,
         'data': <String, dynamic>{
           'i': i + 1,
           'k': 10 * i + 1,
         },
         'benchmarkScoreKeys': <String>['i', 'k'],
       });
+      ab.addBResult(bResult);
     }
     ab.finalize();
 

dev/devicelab/test/task_result_test.dart

@@ -0,0 +1,46 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_devicelab/framework/task_result.dart';
+
+import 'common.dart';
+
+void main() {
+  group('TaskResult fromJson', () {
+    test('succeeded', () {
+      final Map<String, dynamic> expectedJson = <String, dynamic>{
+        'success': true,
+        'data': <String, dynamic>{
+          'i': 5,
+          'j': 10,
+          'not_a_metric': 'something',
+        },
+        'benchmarkScoreKeys': <String>['i', 'j'],
+      };
+      final TaskResult result = TaskResult.fromJson(expectedJson);
+      expect(result.toJson(), expectedJson);
+    });
+
+    test('succeeded with empty data', () {
+      final TaskResult result = TaskResult.fromJson(<String, dynamic>{
+        'success': true,
+      });
+      final Map<String, dynamic> expectedJson = <String, dynamic>{
+        'success': true,
+        'data': null,
+        'benchmarkScoreKeys': <String>[],
+      };
+      expect(result.toJson(), expectedJson);
+    });
+
+    test('failed', () {
+      final Map<String, dynamic> expectedJson = <String, dynamic>{
+        'success': false,
+        'reason': 'failure message',
+      };
+      final TaskResult result = TaskResult.fromJson(expectedJson);
+      expect(result.toJson(), expectedJson);
+    });
+  });
+}